| Mespilon Graham, 1957 |
| Metastenus Walker, 1834 |
| Metastenus cryptognathae (Girault, 1920) |
| Metastenus mexicanus (Girault, 1916) |
| Metastenus townsendi Ashmead, 1904 |
| Metopachia Westwood, 1839 |
| Metopon Walker, 1834 |
| Metopopachia Dalla Torre, 1898 |
| Metopum Agassiz, 1848 |
| Meximalus Boucek, 1993 |
| Meximalus heratyi Boucek, 1993 |
| Miscogasterinae Walker, 1833 |
| Moranila Cameron, 1883 |
| Moranila californica (Howard, 1881) |
| Moranila ceroplastis (R.C.L. Perkins, 1906) |
| Moranila festiva (Masi, 1917) |
| Moranila flaviceps (Girault, 1915) |
| Moranila glabriventris (Girault, 1915) |
| Moranila testaceipes Cameron, 1883 |
| Mormoniella Ashmead, 1904 |